In South America, I would prefer that the devs focus on the pre-Columbian empires. Some interesting concepts have already been discussed in this forum.
In Mesoamerica, the Purepecha Empire (Tarascans) could be an interesting addition. I have recently learned that it was considered a more powerful empire than the “Aztecs”.
As a personal note, I’m grateful to the developers and users who are showing more interest in historical accuracy